Recall, at that point, Apple had only sold 40 million iPads cumulatively, the PC industry was still growing, and smaller tablets—and huge-screen phones—hadn’t yet found their footing. Gartner, the tech analyst firm, had just predicted that tablet shipments would pass 100 million in 2012 and could reach 326 million in 2015, while still expecting growth from the PC industry.

More recent data suggest that tablet sales could potentially pass PC sales this year—or should at least come close—and will almost certainly pass them next year. Gartner now expects tablet sales to pass 270 million this year, versus PC sales around 277 million. By next year, tablet sales could approach 350 million—7% ahead of that 2015 prediction made back in 2011—while PC sales should continue to slide.

This year’s expected growth spurt now seems a bit shaky, as Apple’s iPad sales unexpectedly declined in the first quarter. It’s too early to tell if that was a one-off miss, a sign the iPad’s cheaper competition is getting stronger, or an indication of deeper problems with the tablet concept.

There’s also the (mostly academic) question of how to classify Microsoft’s new tablet-PC hybrid, if it actually succeeds. Historically, Gartner has included these Intel- and Windows-based tablets in its PC stats. Would it be good or bad if a touchscreen tablet props up the same stats used for desktop workstations?

Then there are the further-blurring lines on the other side of the “post-PC” revolution—between tablets and smartphones. With last year’s smartphone shipments near one billion, per Gartner—and inevitable competition between large phones and small tablets—it’s clear that those two categories of devices are how most of the world will be getting online.